在jsp的前端页面的头部插入一个js方法:
<jscript>
function checkUser(){ var result = document.getElementById("userid").value; var password = document.getElementById("userpassid").value; if(result == "" ){ alert("用户名不能为空"); return false; } if(password == "" ){ alert("密码不能为空"); return false; }else{ return true; } }
<jscript>
在form表单里写成这样:
<div> <form id="formid" name="myform" method='post' action='user_login_submit.action' οnsubmit="return checkUser();"> <table width="100%" border="0"> <tr> <td width="60" height="40" align="right">用户名 </td> <td><input type="text" value="" class="text2" name="username" id="userid" /></td> </tr> <tr> <td width="60" height="40" align="right">密 码 </td> <td><input type="password" value="" class="text2" name="userpass" id="userpassid" /></td> </tr> <tr> <td width="60" height="40" align="right"> </td> <td><div class="c4"> <input type="submit" value="" class="btn2" /> </div> </td> </tr> </table> </form> </div> 方法二: function checkUser(){ var result = document.getElementById("userid").value; var password = document.getElementById("passid").value; if(result == "" ){ alert("用户名不能为空"); return false; } if(password == "" ){ alert("密码不能为空"); return false; } document.getElementById("formid").submit(); } form表格的写法,需要写id <form id="formid" method = 'post' action = 'user_login_submit.action' > button按钮的写法如下:<input type="button" value="" class="btn2" onclick = "checkUser();" />
当点击button时,会运行checkUser()的内容,从而进行前端验证非空